Barn owl flight

Abstract

Owls (Strigiformes) are nocturnal birds of prey that are known for their silent flight. For a long time, the underlying mechanisms were not well understood. In a comprehensive study, we have characterized the flight apparatus of one representative of owls, the barn owl (Tyto alba pratincola), to advance beyond the phenomenological description provided so far. The barn owl wing is adapted to slow flight as indicated by a low wing loading, an elliptical shape, a high camber and a specific thickness distribution. Further, feather specializations can be found: 1.) serrations at the leading edge of the wing, 2.) a velvety dorsal surface texture, and 3.) fringes at the inner vanes of remiges. Quantitative characterizations of these structures revealed that serrations had a uniform shape, but the length depended on their position on the wing. The velvety dorsal surface texture differed between the inner and outer vanes which is a consequence of different functions (air flow control, friction reduction). The fringes were observed to merge into neighboring feather vanes by gliding into grooves at the lower wing surface to create a smooth airfoil. Besides anatomical data, material properties and wearing effects of feather keratin of rachises and barbs were obtained. © 2012 Springer Berlin Heidelberg.